I am a Triumph motorcycle fan and owner; I bought this book in order to work on my 1996 Triumph Trophy 1200. As an amateur mechanic and avid do it yourself hobby enthusiast I think this book is a very good start for understanding your triumph motorcycle and allowing you to do some moderately complex repairs and adjustments.
In particular I liked the pictures, diagrams, and exploded views of my motorcycle. The disassembly/assembly instructions where clear and concise, and I especially liked the little technical tips and watch outs for tricky parts or delicate assemblies. I think quite a bit of thought went into the language of the book, it is so easy for professionals mechanics to speak in jargon and acronyms, this book speaks in plain English with only the necessary technical terms needed, and there is a glossary of terms for us newbie's. The chapters are laid out in a progressive sequence starting with routine maintenance and periodic services, trough major engine disassembly and followed up by subsystem detail. The chapter on special tools and techniques is especially interesting because it lets you know how deep you tool chest needs to be in order to complete some of the more complex tasks.
My pet peeve with this book is that there is no comprehensive specifications appendix for torque, clearances, tolerances, pressures etc. It is very frustrating to have to hunt and search through the beginning of each chapter to find the needed information. Also the information is incomplete, for instance I could not find the torque specification for the front sprocket cove bolts, the only reference is to the clutch actuator assembly that attaches onto the cover, those bolts capture the cover and clutch housing together, so I must assume that is the appropriate specification for the entire cover.
For anyone interested in Triumph motorcycle repair, this book is much better than just the owners manual, but not as detailed as the appropriate Triumph shop manual. All the essential information for care and maintenance of your motorcycle is there. If your handy with mechanics tools and can read relatively well, the book works well. I am sure a professional mechanic would not be happy with it, but hey he/she can buy the shop manual.
Well, that's my two cents, I enjoyed the book, I recommend it, and hope you enjoy it as well.